1. Field of the Invention
This invention relates generally to the field of aircraft flight control and more particularly to wing trailing edge systems for maneuvering the airplane, adjusting the aerodynamics for more efficient flight and modifying the airfoil to suit landing and takeoff flight requirements. The invention has particular utility on very large airplanes. These airplanes are designed to be highly efficient, as indicated by the fact that the weight of their structure is to be as small as 25% of the maximum takeoff weight of the airplane. This means that all the structure must be as light as possible, including the flaps and spoilers. Also, the power required to control the flaps and spoilers must be as low as possible, to minimize the weight of the power generators, and the power transmission and utilization equipment.
Further, to be as economically feasible as possible, these airplanes must be able to lift great payloads from runways of conventional lengths. This means that all available wind area should be usable for landing and taking off. This means, in turn, that whereas in conventional airplanes the lift augmenting flaps are used on only part of the wing span and the remaining span is devoted to flight control, on these airplanes the lift augmenting devices must be full span. The implications of this are that the lift augmentation devices must serve also as primary flight controls and therefore must be light and responsive enough to serve as flight controls.
To best meet their economic and mission requirements it is also important that these airplanes be as inexpensive to build and maintain as possible. The implication from this fact on the trailing edge system is that it must provide very good aerodynamic effects while being structurally and mechanically simple.
One example of prior art of particular interest is that disclosed in U.S. Pat. No. 3,478,988, to Age E. Roed. FIGS. 1 and 2 of this disclosure are reproductions of FIGS. 3 and 4 from Roed's patent. FIG. 1 shows Roed's apparatus set for takeoff and FIG. 2 shows it set for approach and landing. This apparatus, although successful in some respects, does not solve the problems or satisfy the criteria above primarily because, as can be seen in both figures, there is a rather abrupt "break" in the upper wing surface where the trailing edge of spoiler 51 comes close to the upper surface of flap 37. This break interferes with smooth flow over the flap, particularly in the approach and landing situation. The subject invention is directed toward providing improved upper surface curvature in trailing edge apparatus in which the spoilers are used in conjunction with the trailing edge flaps for lift augmentation and flight control.